Randomized Trial of Burr-Hole Surgery With or Without Irrigation for Chronic Subdural Hematoma: Impact of Postoperative Pneumocephalus on Recurrence

BACKGROUND AND OBJECTIVES: Although postoperative subdural drainage is established as an effective strategy to prevent recurrence after burr-hole surgery for chronic subdural hematoma, the necessity of intraoperative irrigation remains unclear. We conducted a randomized controlled trial to compare burr-hole surgery with and without intraoperative irrigation, with postoperative subdural drainage performed in both groups, and to explore factors associated with recurrence. METHODS: Between May 2020 and October 2023, 242 patients undergoing initial burr-hole surgery for chronic subdural hematoma were randomized to burr-hole surgery with or without intraoperative irrigation. Postoperative subdural drainage was performed in both groups. The primary outcome was recurrence requiring reoperation within 3 months. Secondary outcomes included perioperative complications, operative time, length of hospital stay, functional outcome, mortality, and postoperative imaging findings. Exploratory analyses were performed to identify factors associated with recurrence using multivariable logistic regression. RESULTS: A total of 242 patients were randomized (irrigation group: n = 114; no-irrigation group: n = 128), and 231 (95.5%) completed 3-month follow-up. Recurrence requiring reoperation occurred in 21 patients (18.4%) in the irrigation group and 12 patients (9.4%) in the no-irrigation group (adjusted risk difference, -9.4%; 95% CI, -18.5 to -0.4; P = .02). There were no significant differences between groups in functional outcome or complication rates.In exploratory analyses, postoperative pneumocephalus volume was independently associated with recurrence (odds ratio per 10 mL increase, 1.31; 95% CI, 1.10-1.56; P = .003). The association between surgical technique and recurrence was attenuated after adjustment for pneumocephalus. CONCLUSION: Burr-hole surgery without intraoperative irrigation was associated with a lower recurrence rate compared with irrigation. These findings suggest that intraoperative evacuation and irrigation may not be necessary when postoperative drainage is performed. Postoperative pneumocephalus may play a key role in recurrence and could represent a modifiable target for improving surgical outcomes.